Passive immunization against nicotine prevents nicotine alleviation of nicotine abstinence syndrome.

Passive immunization against nicotine interferes with its locomotor and pressor effects. The current study determined whether immunization could prevent another nicotine action: the reversal of nicotine abstinence syndrome. IgG containing 4.4-5.6% nicotine-specific antibody was isolated from rabbits immunized with 3'-amino-methyl-nicotine conjugated to a carrier protein. Twenty rats were rendered dependent by 7 days of subcutaneous infusion of 3.15 mg/kg/day nicotine (expressed as the base). Upon termination of nicotine infusion, each rat was injected intraperitoneally with 150 mg of IgG from normal serum (n=13) or from nicotine antiserum (n=7). Twenty-two and one-half hours later, all rats were observed over 15 min for baseline nicotine abstinence signs. Two and one-half hours after baseline observations, seven of the 13 rats pretreated with control IgG and all seven rats pretreated with nicotine-specific IgG were then challenged by 0.12 mg/kg (sc) nicotine. The remaining six rats pretreated with control IgG were challenged with saline alone. All rats were then observed again for abstinence signs. Nicotine injection caused significantly less reduction of abstinence signs in the immunized rats. The nicotine effect in immunized rats was comparable to the saline effect in nonimmunized rats. Immunization also significantly reduced free serum nicotine concentration and nicotine distribution to the brain. These results raise the possibility that immunization might prevent nicotine consumption from relieving the discomforts of smoking cessation.

A nicotine conjugate vaccine reduces nicotine distribution to brain and attenuates its behavioral and cardiovascular effects in rats.

Vaccination of animals to elicit drug-specific antibodies, or the passive transfer of such antibodies from other animals, can reduce the behavioral effects of drugs such as cocaine and heroin. To study the potential application of this approach to treating nicotine dependence, IgG was isolated from rabbits immunized with a nicotine-protein conjugate vaccine. Anesthetized rats received immune IgG containing nicotine-specific antibodies (Nic-IgG) or control-IgG i.v.. Thirty minutes later, rats received nicotine at 0.03 mg/kg i.v., equivalent on an mg/kg basis to the nicotine intake from two cigarettes by a smoker. Compared to control-IgG, Nic-IgG reduced the brain nicotine concentration in a dose-related manner (65% reduction at the highest IgG dose). Pretreatment with Nic-IgG also reduced the distribution to brain of five repeated doses of nicotine (equivalent to the nicotine intake from 10 cigarettes) administered over 80 min. To study blood pressure effects, rats received control-IgG or Nic-IgG 1 day prior to administering nicotine. Nicotine-induced systolic blood pressure increases were attenuated by Nic-IgG in a dose-related manner, and were almost completely blocked by the highest Nic-IgG dose. Pretreatment with Nic-IgG also completely prevented the nicotine-induced stimulation of locomotor activity observed in rats receiving control-IgG. Nic-IgG did not prevent locomotor activation from cocaine, demonstrating its specificity for nicotine. These data demonstrate that the administration of nicotine-specific antibodies can reduce or prevent some of the pharmacokinetic, cardiovascular, and behavioral consequences of nicotine in rats. Effects were observed at nicotine doses and nicotine serum concentrations equal to or exceeding those typically associated with nicotine exposure in cigarette smokers. A potential role for immunization in the treatment of nicotine dependence is suggested.

Antigenic determinants of Staphylococcus aureus type 5 and type 8 capsular polysaccharide vaccines.

Bacterial capsular polysaccharides (CP) are carbohydrate polymers comprised of repeating saccharide units. Several of these CP have side chains attached to their backbone structures. The side chains may include O-acetyl, phosphate, sialic acid, and other moieties. Those moieties represent the immunodominant epitopes and the most functional ones. The clinically significant Staphylococcus aureus type 5 CP (CP 5) and type 8 CP (CP 8) are comprised of a trisaccharide repeat unit with one O-acetyl group attached to each repeat unit. The immunogenicity of these CP and the functionality of antibodies to the backbone and the O-acetyl moieties were investigated. Immunization with the native CP conjugates (CP with 75% O-acetylation) elicited a high proportion of antibodies directed against the O-acetyl moiety. Nonetheless, all of the vaccinees produced antibodies to the backbone moieties as well. Conjugate vaccines made of de-O-acetylated CP elicited backbone antibodies only. Antibodies to both backbone and O-acetyl groups were found to be opsonic against S. aureus strains which varied in their O-acetyl content. Absorption studies with O-acetylated and de-O-acetylated CP showed that (i) native CP conjugates generated antibodies to both backbone and O-acetyl groups and (ii) O-acetylated isolates were opsonized by both populations of antibodies while the non-O-acetylated strains were predominantly opsonized by the backbone antibodies. These results suggest that S. aureus CP conjugate vaccines elicit multiple populations of antibodies with diverse specificities. Moreover, the antibodies of different specificities (backbone or O-acetyl) are all functional and efficient against the variations in bacterial CP that may occur among clinically significant S. aureus pathogenic isolates.

A simple, quantitative, reproducible avidin-biotin ELISA for the evaluation of group B streptococcus type-specific antibodies in humans.

Type-specific antibodies to the capsular polysaccharides (CP) of group B Streptococcus (GBS) are protective. Historically, the radioactive antigen-binding assay (RABA) has been used to determine GBS antibody levels. This method measures total immunoglobulin and employs the use of radioactive materials. We have developed an avidin-biotin ELISA that is less hazardous and is able to measure GBS Ia, Ib, II or III CP specific IgG. To avoid inconsistent binding to the plate, the CPs from GBS Ia, Ib, II and III were derivatized using adipic acid dihydrazide (ADH) and subsequently biotinylated without altering their antigenic epitopes and bound to avidin coated plates. Plasma from three different human subjects immunized with a tetravalent CP vaccine were used to prepare IgG references for Ia, II and III, respectively, thus rendering the assay quantitative for those types. The assay is able to detect nanograms per milliliter of GBS Ia, Ib, II or III specific antibody. This method is reproducible, sensitive and correlates with RABA by 76%.

Safety and immunogenicity of a tetravalent group B streptococcal polysaccharide vaccine in healthy adults.

Proposed strategies for prevention of neonatal group B streptococcal (GBS) infection have included active immunization of pregnant women and passive immunization of high-risk infants with hyperimmune GBS globulin derived from vaccinated plasma donors. To explore the feasibility of a program for generating hyperimmune GBS globulin, we evaluated the safety and immunogenicity of a candidate multivalent GBS vaccine containing purified polysaccharide from types Ia, Ib, II, and III among subjects most likely to develop an immune response following vaccination, i.e. those with pre-existing antibody to GBS. Thirty volunteers prescreened for serum antibody to type III GBS were immunized with a single subcutaneous injection of vaccine containing either 10, 25, or 50 micrograms of each polysaccharide type (Group 1). An additional ten volunteers prescreened for antibody to type Ia were vaccinated with the 50 micrograms dose (Group 2). Vaccination was generally well tolerated with minor reactions occurring in 27% of subjects. Using a quantitative enzyme-linked immunosorbent assay (ELISA), the seroconversion rates (> or = fourfold rise) and geometric mean antibody concentration (GMC in microgram IgG ml-1) 6 weeks after vaccination in Group 1 to type Ia, II, and III were 33% (GMC 5.2), 17% (GMC 3.6), and 70% (GMC 43.4), respectively. Quantitative titers were not available for type Ib, but a fourfold rise in ELISA units was seen in 13% of subjects. In Group 2, seroconversion rates to type Ia and III were 90% (GMC 73.4) and 40% (GMC 22.2), respectively. No significant dose-response effect was detected. Combined analysis of Groups 1 and 2 demonstrated that subjects with prevaccination antibody concentrations > 2 micrograms IgG ml-1 had significantly higher type-specific antibody concentrations following vaccination compared with subjects possessing lower levels of antibody before immunization. We conclude that our tetravalent GBS polysaccharide vaccine is safe but only modestly immunogenic in healthy seropositive adults. More potent vaccines will be required for public health use.